The present invention relates to a self-propelled agricultural harvesting machine that includes an installed front attachment which is supported when in a non-working position by at least one carrier wheel system which is in contact with the ground.
The output of agricultural harvesting machines continues to increase, thereby requiring the use of increasingly larger and heavier front attachments. Typically, headers of combine harvesters are detached from the combine harvester and placed on a trailer in order to be hauled on the road. In contrast, corn headers and corn pickers are typically not detached from forage harvesters in preparation for travel on the road; instead, they remain attached to the forage harvester. In preparation for travel on the road, these front attachments can be folded using different types of folding mechanisms, in order to decrease their width, as is the case with grain-cutting devices. However, the fact that the permissible axle load, in particular on the drive axle of agricultural harvesting machines, is stipulated by various standards poses a problem given that the front attachments are becoming increasingly wider and heavier.
DE 199 18 551 makes known an agricultural harvesting machine designed as a forage harvester that includes an intermediate attachment on the front side that accommodates an agricultural working device. To ensure that the load of the agricultural working device need not be supported exclusively by the carrier vehicle axle situated at the front relative to the direction of travel, it is provided in at least one embodiment that carrier wheels are assigned to the intermediate attachment that make it possible for at least a portion of the mass of the agricultural working device to be supported on the ground via these carrier wheels during travel on the road. However, in order to adapt the carrier wheels to the intermediate attachment of the agricultural harvesting machine, this intermediate attachment must be stiffened considerably since extreme impact loads may occur when traveling over uneven ground, and these impact loads must be absorbed by the intermediate attachment. Given that the axles of the carrier wheels are located directly on the intermediate attachment of the agricultural harvesting machine, the carrier wheels are unable to move vertically relative to this intermediate attachment. As a result, when the intermediate attachment is lifted, the load that is transferred from the carrier wheels to the ground decreases gradually and reaches zero in the instant at which the carrier wheels have lost their contact with the ground. At this instant, the carrier wheels are no longer performing a support function, and the entire load acts on the front axles of the harvesting machine.
EP 1 261 247 B1 describes a device for use with front attachments of self-propelled combine harvesters that follows the ground contour and is designed to react quickly and exactly to uneven ground surfaces by displacing the front attachment vertically and transversely. This object is attained using different electro-hydraulic connections between the control and operating elements that needed in order to follow the ground contour. Although this results in an efficient method of following the ground contour, the weight of the front attachment and the feed rake is introduced directly into the front axle of the combine harvester; the load is not distributed, which is an important requirement in the case of wide, heavy front attachments in particular. The problem of load distribution that occurs when the front harvesting attachment has assumed the transport position is not solved.